The organization of chromatin on the structural gene sequences and the ribosomal gene sequences in yeast will be analyzed by nuclease digestion. DNA from staphylococcal nuclease and pancreatic deoxyribonuclease I digests of intranuclear chromatin will be transferred onto nitrocellulose filters and hybridized with cDNA (for structural genes) and ribosomal DNA probes. Correlation of the pattern of sequences homologous to the probes with the bulk patterns will tell whether the gene sequences are protected in the characteristic nucleosomal repeat pattern (and therefore contain nucleosomes) and whether certain fine structure aspects such as clustering of linker sizes and phasing are characteristic of genes. The cloned cytochrome c gene of yeast will be used to determine whether there is absolute phasng on one particular cellular sequence by hybridization to mononucleosome DNA. The nucleosomal arrangement of genes, clustering of linker sizes and phasing will also be studied in stationary phase yeast which show decreased transcription levels and in yeast undergoing meiosis to assess the effects of these changes in life state on the gene chromosomal structure.